Spark plug



H. WALTERS Aug. 2 7, 1935.

SPARK PLUG Filed Feb. 12, 1934 ATTO RN EYS Patented Aug. 27, 1935 PATENT OFFICE SPARK PLUG Herbert Walters, Detroit, Mich, assignor or onehalf to Howard D. House, Detroit, Mich.

Application February 12, 1934, Serial No. 710,83!

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w This invention relates to a spark plug particularly adapted for use in connection with internal combustion engines, and its object is to provide a self-cleaning plug the terminals of 5 which will not become fouled and short circuited when the engine is pumping an excessive amount of oil. A further object is to provide an insulating core or porcelain the construction of which I is. such as to preclude its cracking in use and f to provide a. strong and rigid body so arranged as to guard against injury by unequal expansion, the major portion of said body being inclosed and firmly seated within an enclosing casing which forms a chamber around the porcelain having restricted communication with the interior oi the engine cylinder at the inner end of the plug adjacent its terminals, whereby upon compression in the cylinder, this chamber is filled with explosivemixture which is exploded therein 2 upon the down stroke of the engine piston and the products of this combustion shoot past the terminals cleaning the same.

-.A further object is to provide certain other new and useful features, all as hereinafter set 25 forth, reference being bad to the accompanying drawing in which Figure 1 is a transverse longitudinal section through a complete structure illustrative of an embodiment of the present invention;

3 Fig. 2 is a transverse section substantially upon the line 2-2 of 1;

Fig. 3 is a side elevation of the porcelain core detached; and

Fig. 4 is a lower end view of Fig. 3.

5- The phigcomprises a metal casing comprising a base 1 formed with a sciewthreaded nipple 2 adapted to be received in a bore communicating with the combustion chamber oi an explosion I engine in the manner well known in the art.

40 The base part I is further formed with a conical bore 3 which is countersunk at its upper end as indicated at 4. The base part has an upwardly extending screwthreaded portion I receiving an internally threaded hollow body or casing 8,

45 the latter having an internal shoulder I adapted to oppose the portion 5 and an end wall 8 formed with a central opening 9 and an annular inclined shoulder III.

A porcelain insulating body II has an axial w conductor rod l2 enclosed in a. protective sheath or tube i3 molded in the body to secure it therein, the

rod extending beyond the lower end of the porcelain to form an electrode l4 and is screwthreaded at its upper end to screw into said tube and to 55 form a terminal post receiving a clamping nut (Cl. Inn-169) l5 and also to provide tor longitudinal adjustment or said rod in said tube. The porcelain body H has a. substantially conical lower end portion [6 received in the conical bore 3, and an annular outwardly'inclined shoulder l1 received in the countersunk part 4. The upper projecting end portion of the porcelain body II is formed cylindrical as at l8 and this portion extends through the central opening 9 in the end wall 8 of the casing 8, projecting a short distance 10 therebeyond to'insulatefrom the casing, a lead wire connected to said rod. On the porcelain body within the casing 6 adjacent the end wall thereoi, there is formed an enlargement forming an inclined shoulder is to oppose said shoulder ID of the casing and that portion of said body between the enlargement forming the angular shoulder i1 and this enlargement of the porcelain body is reduced in diameter as at 2|! to provide a space between said body and casing wall and form a combustion chamber 2| in said casing surrounding said body. Furthermore the porcelain body is formed with a plurality of grooves 22 in the exterior of its conical end portion l6, cutting through the adjacent enlargement or shoulder l'! on the body and providing passages leading from the chamber 2| and opening through the lower end of the conical portion of the body adjacent the electrode I4 and an electrode 23 on the nipple 2, which electrode is bent to lie adjacent to but spaced from the electrode l4 in the usual manner to provide a spark gap.

In assembling the device a compressible ring gasket 24 is placed in the countersink 4 between the shoulder formed thereby and the shoulder H with the conical end it of the porcelain body H seated in the conical bore and a similar ring type compressible gasket 25 is then placed on the inclined shoulder is and the casing i is screwed onto the portion 5 of the base, securely 4o clamping said insulating body ll between the shoulders l0 and 4 on the casing 6 and base respectively. When the shoulder I approaches the portion 5 the gaskets 24 and 25 will have become compressed and provide an eflicient sealing means so that gases cannot enter or escape from the chamber 2| except through the grooves 22, and the porcelain insulation is rigidly held in the casing with all except its end portions l6 and I8 spanning the chamber 2|, so that a substanw tially even heat will be applied to the insulator throughout substantially its entire length by combustion in said chamber and unequal expansion of the procelain will be obviated, thus preventing cracking thereof. u

When the present plug is mounted in a cylinder of an internal combustion engine and the compression stroke takes place a quantity of combustible gases will be forced into the chamber 2| through the passages 22 and when the charge in the cylinder is fired in the usual manner these gases in the chamber 2| will also be fired and expand rapidly to create a blast through the grooves 22 upon the power stroke of the engine piston, the blast thus created being directed against the electrodes l4 and 23 by said grooves or passages, setting up a flow of gases of sufficient velocity to efficiently clean the electrodes of deposits before such deposits have had suflicient time to become firmly adhered thereto and the burning of the points is also prevented thereby.

The gap between the points or electrodes I 4 and 23 may be quickly and accurately adjusted Without removing the plug from its mounting in the engine cylinder, by mounting the rod I2 slidably in the tube l3 and screwing this rod into or out of said tube, thus providing a very quick setting of the spark gap while the engine is running to secure the most efiective adjustment.

Although a specific embodiment of the present invention has been illustrated and described it is to be understood that various changes may be made Within the scope of the appended claims without departing from the spirit of the invention, and such changes are contemplated.

What I claim is:

1. A spark plug including a. metal casing forming a combustion chamber having restricted communication with the interior of an engine cylinder, an insulating body provided with an electrode projecting from the inner end of said body, said body extending across said chamber and confined adjacent its ends within said casing, whereby said body is secured adjacent its ends with the main portion thereof enclosed within said chamber and heated by combustion within said chamber to give substantially equal expansion substantially throughout the length of said body.

2. A spark plug including a metal casing forming a combustion chamber having restricted communication at its inner end with the interior of an engine cylinder to which the plug is applied in use, said casing being formed with seats at the inner and outer ends of said chamber, and an insulating body seated adjacent its ends upon said seats with the main portion of said body extending'across said chamber and in spaced relation to the side walls thereof, said body being provided with an electrode at its inner end.

3. A spark plug including a metal casing having a screwthreaded nipple at its inner end formed with a tapered bore, said casing forming a combustion chamber having restricted communication through said nipple with the interior of an engine cylinder to which the plug is applied in use, and an insulating body having a tapered lower end portion to seat in said tapered bore and an upper end portion seated upon the upper end wall of said casing to confine said body in said casing with the main portion of said body extending across the chamber of the casing with said body spaced from the side walls of said chamber, said body having an electrode projecting from its lower tapered end.

4. A spark plug including a casing forming a combustion chamber and having an opening through the end thereof which end is applied to an engine cylinder in use, and an insulating body mounted in said chamber and extending across the same and seated in said opening with a passage opening into said chamber at one end and at its opposite end adjacent the end of said body forming the closure for said opening, said end of said body having an electrode adjacent the outlet end of said passage, whereby products of combustion from said chamber will be directed by said passage over said electrode projecting from said body.

5. A spark plug including a metal casing forming a combustion chamber and having an opening in each end thereof with an annular seat adjacent each opening, an insulating body provided with an electrode projecting from one end thereof, said body having shoulders adjacent its ends to seat in said seats and hold said body within said casing and extended across said chamber in spaced relation to the side walls thereof, the end of said body provided with said electrode and said casing forming a restricted passage open at one end into said chamber and at its opposite end adjacent said electrode.

6. A spark plug comprising a casing forming a combustion chamber and formed with a tapered bore in its inner end, and an electrode carrying body formed with a tapered lower end to seat in said bore, said tapered end being formed with external longitudinal grooves forming passages open at their upper ends into said chamber of said casing and at their lower ends adjacent said electrode.

7. A spark plug as characterized in claim 6, and wherein said casing is formed with an opening in the upper end wall of its chamber opposite said tapered bore in its lower end, and wherein said body has an upper end portion to engage in and close said opening in said end wall, said casing being formed with annular seats at the inner end of bore and opening for the seating thereon of annular shoulders on said body, and said casing being formed in two parts to be drawn toward each other to clamp said body within said casing and seated upon said seats.

HERBERT WALTERS. 

